linux-kernel - Re: [PATCH 1/1] Fixed to BUG_ON to WARN

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Message-ID: <86a4ccec-fa16-ce16-a5a9-e827fc5b781a@gmail.com>
Date:   Wed, 14 Dec 2016 14:58:42 +0200
From:   Tariq Toukan <ttoukan.linux@...il.com>
To:     Leon Romanovsky <leon@...nel.org>,
        Ozgur Karatas <okaratas@...ber.fsf.org>,
        Tariq Toukan <tariqt@...lanox.com>
Cc:     "yishaih@...lanox.com" <yishaih@...lanox.com>,
        netdev <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] Fixed to BUG_ON to WARN_ON def

Thanks Ozgur for your report.


On 12/12/2016 8:18 PM, Leon Romanovsky wrote:
> On Mon, Dec 12, 2016 at 03:04:28PM +0200, Ozgur Karatas wrote:
>> Dear Romanovsky;
> Please avoid top-posting in your replies.
> Thanks
>
>> I'm trying to learn english and I apologize for my mistake words and phrases. So, I think the code when call to "sg_set_buf" and next time set memory and buffer. For example, isn't to call "WARN_ON" function, get a error to implicit declaration, right?
>>
>> Because, you will use to "BUG_ON" get a error implicit declaration of functions.
> I'm not sure that I followed you. mem->offset is set by sg_set_buf from
> buf variable returned by dma_alloc_coherent(). HW needs to get very
> precise size of this buf, in multiple of pages and aligned to pages
> boundaries.
>
>>          sg_set_buf(mem, buf, PAGE_SIZE << order);
>>          WARN_ON(mem->offset);
> See the patch inline which removes this BUG_ON in proper and safe way.
>
>  From 7babe807affa2b27d51d3610afb75b693929ea1a Mon Sep 17 00:00:00 2001
> From: Leon Romanovsky <leonro@...lanox.com>
> Date: Mon, 12 Dec 2016 20:02:45 +0200
> Subject: [PATCH] net/mlx4: Remove BUG_ON from ICM allocation routine
>
> This patch removes BUG_ON() macro from mlx4_alloc_icm_coherent()
> by checking DMA address aligment in advance and performing proper
> folding in case of error.
>
> Fixes: 5b0bf5e25efe ("mlx4_core: Support ICM tables in coherent memory")
> Reported-by: Ozgur Karatas <okaratas@...ber.fsf.org>
> Signed-off-by: Leon Romanovsky <leonro@...lanox.com>
> ---
>   drivers/net/ethernet/mellanox/mlx4/icm.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/icm.c b/drivers/net/ethernet/mellanox/mlx4/icm.c
> index 2a9dd46..e1f9e7c 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/icm.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/icm.c
> @@ -118,8 +118,13 @@ static int mlx4_alloc_icm_coherent(struct device *dev, struct scatterlist *mem,
>   	if (!buf)
>   		return -ENOMEM;
>
> +	if (offset_in_page(buf)) {
> +		dma_free_coherent(dev, PAGE_SIZE << order,
> +				  buf, sg_dma_address(mem));
> +		return -ENOMEM;
> +	}
> +
>   	sg_set_buf(mem, buf, PAGE_SIZE << order);
> -	BUG_ON(mem->offset);
>   	sg_dma_len(mem) = PAGE_SIZE << order;
>   	return 0;
>   }
> --
Thanks Leon for the patch. It is the right way to do so.
Reviewed-by: Tariq Toukan <tariqt@...lanox.com>

We will submit Leon's patch in a new email.

Regards,
Tariq
> 2.10.2
>